Device for t



Oct. 14, 1958 H, L. GRUBE 2,855,770

DEVICE FOR THE AUTOMATIC RE-LIGHTING OF GAS BURNERS Filed June 30, 19541 l i L/ 2 4 I i l FIG.2

19 18v 15d .11 2* s3 INVENTOR.

HANS LUDOLF' GRUBE BY [44M M E a) ATTORN YS Unite I? DEVICE FOR THEAUTOMATIC RE-LIGI-ITING OF GAS BURNER-S Hans Ludolf Gruhe, Hanan (Main),Germany, assignor to W. C. Heraeus G. in. b. H., Hanan (Main), Germany,a corporation of Germany 'The present invention relates to gas burners,particularly those intended for use with relatively heavy gaseoushydrocarbons such as propane or butane. It is an object of the inventionto provide protection against the gas flames becoming accidentallyextinguished. A further object is to provide improved means which ensureautomatic relighting when the gas flame has become extinguished underexternal influences such for example as strong draughts of air.

YA further object of the invention is to solve this problem in aprogressive and technically advantageous manner. According to theinvention there is arranged, facing the gas-outlet aperture of theburner orifice at States atet1t O 7 the location of the burning gasflame, a highly heatresistant body capable of storing'heat, whichcarries a metallic catalyst effecting the ignition. Particularlysuitable for the purpose of the invention is a body, capable ofheatstorage, made of customary ceramic materials, such for example assteatite.

The device according to the-invention is mainly intended for gas burnersdestined for use in the open air, particularly in equipment for street,rail and sea traffic, for example in signal lamps and in railway-pointheating devices, where they are liable to be exposed to extreme externalinfluences, such as humidity or moisture, draughts of air which, in thecase of employment in railway-point heating apparatus may be generatedby passing railway trains, further gales and vibrations and variationsof position, itis necessary for these circumstances to be taken intoconsideration in the construction of the apparatus.

It is therefore a further object of the invention to ensure that'theheat-storage device will maintain the catalyst sufficiently warm afterextinction for an extended period of time, up to the length of a fewminutes, to enable it to relight the hydrocarbon-air mixture when theinfluence of the interfering circumstance has terminated. A ceramicfront member heated by the burning gas flame in the constructionaccording to the invention,'wl1ich for example may consist of steatite,will after extinction of the gas flame yield its heat relatively slowlyto the surrounding air or to a passing draught of cold air, and maintainthe metal catalyst connected with it at a sufliciently high temperatureto ensure that as soon as the combustible gas-air mixture passes itagain after cessation of the interference, the catalyst will be raisedto bright incandescence and is thus enabled to relight the gas-airmixture within a few seconds.

Two gas-burner constructions according to the invention shallnow beexplained by way of example with reference to accompanying drawings.

Fig. l is a side elevation showing the end of a gas burner in which aheat-storing ignition front member according to the invention has beenmounted in front of its gas outlet aperture, part of the body beingbroken away to show the interior.

Fig. 2 is an axial section, showing a different con 2,855,770 PatentedOct. 14, 1958 Ice struction of an ignition front member according'to theinvention.

Fig. 1 illustrates a simple embodiment of the invention. A hollowcylindrical ceramic body 1 having the size of a normal ceramic burnermouthpiece is arranged approximately in the middle of the gas flame.Across the cylindrical bore of the heat-storing body 1, preferably atthe lower aperture thereof or else in its central portion, there isdisposed a screen plate 2 having multiple perforations, which serves toensure thorough mixing of the combustible gas with air and to reduce theflow velocity. Extended across that aperture of the hollow ceramiccylinder 1, through which the gas-air mixture flows out, there isarranged a metal catalyst 3, preferably consisting of platinum, in theform of a netting or of several wires, which serves to effect theignition. Itis advisable for the ceramic heat-restoring body to be alsoimpregnated with platinum metal, in order to increase still further thereliability of ignition. The ceramic heat-storing body is connected withthe burner mouth piece by means of a framework 4 which preferablyconsists of two rods made of temperature-resistant material. v

The distance between the hollow ceramic body and the burner mouth pieceis preferably determined in such manner according to the oxygenrequirement of the combustible gas and to the oxygen content of the gasmixture flowing out of the burner head that the distance is the greater,the less the air content of the mixture is and the higher the oxygenrequirement of 'the pure gas is; for the quantity of air admixed andthus the inflammability of the mixture increases up to a predeterminedupper limit with the distance from the burner mouthpiece. Since only afraction of the gas-air mixture will flow through the heat-storingceramic body, it is only necessary for this small quantity of gas to beignited.

Fig. 2 illustrates an ignition attachment which constitutes a furtherdevelopment in various respects. According to the invention it mainlyconsists of a hollow cylinder 11 of highly heat-resistant material,preferably of ceramic material, and is mounted directly upon the burnermouthpiece proper, into which it is screwed with the help of ascrew-threaded projection 16 of the attachment member. A substantialpart of the catalytically acting platinum or other platinum metals ofsuitable catalytic action is distributed in the form of an impregnationover the surface of the porous, non-metallic, heat resistant smallceramic bodies 19, so called ignition pills the surface of which islarge relative to their volume, and which are threaded on wires 18 ofplatinum or platinum metals or supported thereon. These pills are thusexposed in such a manner to the flow of gas or to the flame that theyare heated when the flame is burning and that when the flame has becomeextinguished they will, due to their highly heat-conductive metalconnection with the wall of the heater accumulator 11, remain for arelatively long time at a temperature which will substantially assistcatalytic reignition when the interference has ended.

The wire netting 18, which may be flat or funnel'shaped, and whichcarries the ignition pills, is advantageously held in heat-conductivecontact with the surface of the heat accumulator by means of a ring 13made of highly oxidation resistant material, for example of thesiliconor of any suitable ceramic material may be screwed into theoutlet aperture 15 to seeu rethe annularframe l 'l'i."

In order to increase reliability operation the shell of the ceramicheat-storage member is preferably provided with suction passages 14leading to the outer air, which ensure adequate supply of secondary'airto the gas flame and which preferably should form an acute angle withthe direction of gas How in order to increase. the suction effect andthus to assist the introduction of air. Advantageously furthermoreflames are arranged to originate not only fromthe front aperture 15 butalso from lateral apertures 15a of the heat storage member 11. A screenplate 17, the object of which is to thoroughly mix the burner gases andprimary air forms a further construe tional elementand is placed in thegas-entry aperture facing'the burner.

As material for the porous ceramic bodies referred to as ignition pills19 meerschaum and steatite have been foundvery satisfactory but otherceramic materials may be just as suitable.

Practical experience has shown that the ignition attachment according toFig. 2, is distinguished not only by great reliability of. operation butalso by its convenience of. handling which is due to its short lengthand its consequent relatively low sensitivity to impacts and vibrations.Due to the high porosity of the ceramic ignition pills 19, the catalyticaction of the platinum impregnated surfaces is particularly high so thatcatalytic ignition will take place at substantially lower catalysttemperatures than. in the case of bright platinum wires. The shell ofthe ceramic heat-storage member protects the burners against theexternal draughts of air to which they are liable to be greatly exposedfor example when used as signal lamps or in railway-point heatingapparatus. or other apparatus for use in street, rail and sea traffic.Also the danger of soiling and the. influence of moisture upon thesensitive ignition pills is thereby greatly reduced.

Although the usual highly heat-resistant ceramic ma terials such assintered aluminum oxides or steatite are particularly recommended forthe manufacture of the heat-storage member,"there is no objection to thelatter and other parts of the apparatus being made fromhighly oxidationresistant metal alloys for example of the Si-Cr-Al-Fe alloy known underthe registered trade mark Sicromal or of sintered cerarno-metallicmaterial consisting of metals or metal-oxide mixtures, which aredistinguished by relatively great resistance to temperature changes.

The provision of the inclined lateral passages 14 for the supply ofsecondary air also greatly contributes to the desirable qualities ofthis embodiment, since it allows the suction effect of the gas flame tocome more strongly into effect so as to ensure an adequate supply of aireven when employing what may be referred to as heavy gaseoushydrocarbons which, as compared with methane and ethane, have a highmolecular weight. The invention is however also of advantage in burnerswhich are fed with ordinary gaseous hydrocarbons such as methane andethane.

Preferably devices are additionally provided which by utilising theinjector effect of the gas flow ensure good admixture of air to theburning gas, even in the case when the flame has become extinguished,thus preventing complete displacement of the air from the ignitionchamber of the heat storage member by the combustion gas.

The device according to the invention is mainly intendedfor burners fedwith gaseous hydrocarbons to safeguardtheflame against extinction .orrelight it automatically. It is particularly suitable for gas burnerswhich are used in the open air, for example for burners used in railwaysystems for preventing the freezing over of rail- Way points or for thethawing of frozen points, in which case awhole series of gas burners arearranged side by side in a single device. In this case, in which the gasflames are. liable to be blown. out by the wind caused by the movementof passing. rail .vehicles, the present in vention provides a decisiveremedy by on the one hand reducing the danger of extinction and on theother hand in any case ensuring automatic re-ignition even afterrelatively long interruptions which may extend over several minutes.

Similar conditions occur in sea traflic, where for example buoys andlamps equipped with gas burners are generally exposed to strong seawinds or gales.

The invention has been found particularly useful when the burners arefed with heavy gaseous hydrocarbons such as propane and butane. These,as is known, require several times the volume of air which is requiredfor the quantitative combustion of town gas or of ethane or methane. Ithas been previously endeavoured to take this fact into consideration byemploying for the ignition of burners fed with propane or butane insteadof ordinary platinum catalysts, one or several platinum coils; thesecoils however, hadfirst to be raised to dark red glow-heat temperatureby electrical resistance heating in order to enable them to ignite thegas mixture rich in air. The same effect is obtained in a much simplerand more economical manner by the device according to the presentinvention.

I claim:

l. A device for the automatic re-lighting of a gas flame, comprising aheat resistant body capable of storing heat, a'catalyst supported by theheat resistant body in the path of flow of a gas-air. mixture, and theheat storing body being mounted to receive gas from a supply source.

2. A device, according to claim 1, wherein the heatstoring body consistsof ceramic material.

3. A device, according to claim 1, wherein the heatstoring body consistsof a highly oxidation resistant metal alloy.

4. A device, according to claim 1, characterized in that theheat-storing body is made of a sintered ceramometallic material composedof metal and metal oxides.

5. A device for the automatic re-lighting of a gas fed to a burner,comprising a cylindrical shell of highly heat resistant and heat-storingmaterial carrying metallic catalyst, said cylinder shell arranged infront of the gas supply aperture of the burner so that the burner flamewith its hot zone extends through said shell, and said shellencompassing, arranged crosswise to its cylinder axis, and a platinumwire netting in good heat conducting contact with the shell.

6. A device for the automatic re-lighting of a gas fed to a burnercomprising a highly heat resistant cylindrical shell body capable ofstoring heat, provided with a gas entranceaperture at one end and with aflame outlet aperture at its opposite end and openings in the cylindershell for the .admission of air, said body being mounted directly uponthe burner mouthpiece, so that the burner flame extends through saidshell in the direction of the.

longitudinal axis thereof, including porous bodies of heat resistant andheat storing material impregnated with platinum mounted within thecylinder shell crosswise to the flow of gas and carried by a wirenetting of platinum metal, said netting being secured on the inner wallof said heat storing body in heat conducting contact with said body.

7. A device, according to. claim 6, wherein passages are provided whichextend through the cylinder shell adjacent the gas-entry end at an acuteangle to the direction of the flow of gas, to supply air under thesuction effect of the fiow of gas.

References Cited in the file of this patent UNITED STATES PATENTS757,219 Oberlander Apr. 12, 1904 1,120,363 Berthold Dec. 8, 19142,073,448 Fruth et al. Mar. 9, 1937 2,558,061 Schmitt June 26, 1951

